1. Technical Field
The present invention relates to a technical field of an electrooptical apparatus, for example, a liquid crystal apparatus, an electronic device having such an electrooptical apparatus, and an apparatus and a method for detecting outside light used in such an electrooptical apparatus.
2. Related Art
Examples of an electrooptical apparatus include a liquid crystal apparatus in which liquid crystal is disposed between a pair of substrates as an electrooptical substance. In such a liquid crystal apparatus, liquid crystal is put in a predetermined orientation state between a pair of substrates constituting, for example, a liquid crystal panel. By applying a predetermined voltage to the liquid crystal in each pixel formed, for examples in an image display region and thereby changing the orientation and order in the liquid crystal and thereby modulating light, gradation display is performed.
It is known that the visibility in such a liquid crystal apparatus changes depending on the brightness of the surroundings (for example, the light intensity of outside light). For example, when the surroundings of the liquid crystal apparatus are relatively bright, increasing the luminance of the liquid crystal apparatus (specifically, the luminance of light from the backlight) improves the visibility. When the surroundings of the liquid crystal apparatus are relatively dark, it is not necessary to increase the luminance of the liquid crystal apparatus (specifically, the luminance of light from the backlight) to improve the visibility. To realize such a configuration, JP-A-2000-131137 discloses a technique to provide a light sensor on a substrate of a liquid crystal panel constituting a liquid crystal apparatus and to control the luminance of light from a backlight depending on the light intensity of outside light of the surroundings detected in the light sensor. JP-A-2007-72243 discloses a technique to detect the light intensity of outside light while light emission from a backlight is stopped in order to prevent deterioration in accuracy of detection of outside light caused by light from the backlight. In particular, JP-A-2007-72243 discloses stopping light emission from a backlight during a vertical blanking interval.
However, a vertical blanking interval is not constant but differs according to the model or specification of each liquid crystal apparatus. Therefore, if a vertical blanking interval is shorter than the time taken for a light sensor to detect the light intensity of outside light, the light sensor cannot detect the light intensity of outside light. If, to avoid such a technological problem, light emission from a backlight is stopped for a time longer than the time taken for a light sensor to detect the light intensity of outside light, a flicker is caused and the display quality is thereby deteriorated.